Device for deflecting the cathode-ray in cathode-ray tubes



1955 B. w. v. I. $CHENAU 2,722,621

DEVICE FOR DEFLECTING THE CATHODE-RAY IN CATHODE-RAY TUBES Filed Oct. 5, 1950 3 Sheets-Sheet l IN VEN TOR.

BERNARDUS WILLEM VAN INGEN SCH NAU BY AGENT Nam v 1955 B w v. I. SCHENAU 2,722,621

DEVICE Fo'R DEFLECTING THE CATHODE-RAY IN CATHODE-RAY TUBES Filed Oct. 5, 1950 5 Sheets-Sheet 2 INVENTOR.

BERNARDUS WILLEM VAN INGEN SCHENAU AGENT Nov. 1, 1955 B. w. v. x. SCHENAU 2,722,621

DEVICE FOR DEFLECTING THE CATHODE-RAY IN CATHODERAY TUBES Filed Oct. 3, 1950 3 Sheets-Sheet 5 INVENTOR.

BERNARDUS WILLEM \gl N INGEN SCHENAU AGENT United States Patent DEVICE FOR DEFLECTING THE CATHODE-RAY IN CATHODE-RAY TUBES Bernardus Willem Van Ingen Schenau, Eindhoven, Netherlands, assignor to Hartford National Bank and Trust Company, Hartford, Conn, as trustee Application October 3, 1950, Serial No. 188,146

Claims priority, application Netherlands October 4, 1949 7 Claims. (Cl. 31376) This invention relates to a deflecting coil system for cathode-ray tubes.

In the prior art such coils were usually constituted by two halves each of which comprised a large number of turns which involved several disadvantages because of their complicated form. Thus, manufacture of such coils is fairly expensive and the halves are diflicult to reproduce. Furthermore, since the turns must be insulated from each other, the space factor is low, viz. approximately 0.2, and consequently the coils are comparatively bulky. Moreover, such coils are space wasting since high voltages which appear across the coils, especially during the fiy-back of the sawtooth current flowing through the coils, require the coils to be surrounded by suitable insulation and additional insulation must be provided between the coils, which leads to additional loss of space.

Finally, the adjustment of such coils is difficult and complex and can only be carried out empirically.

The deflecting coil system according to the invention avoids the foregoing disadvantages. in accordance with the invention the deflecting coil system comprises one or more rigid turns.

The manufacture of such coils which comprise one or more rigid turns is very simple and this coil system can be readily duplicated. rigid, they need not engage one another except at one or more points which are determined by the shape of the turns so that insulating material will only be required locally. Furthermore, the coil may be made self-supporting so that a particular sleeve for supporting the turns is not required.

Consequently, the coil may be applied directly to the wall of a cathode-ray tube, which decreases the deflection energy required.

Adjustment of the coils may be made during manufacture by employing a simple templet, thus simplifying the adjusting operation.

The invention will be described in greater detail with reference to the appended drawing in which:

Figures 1 and 2 show a deflecting coil of two turns which, after being deformed into the shape shown in Figures 3 and 4, constitute a coil which is shown in front view and in rear view in Figures 5 and 6, respectively.

Figure 7 shows a deflection coil constituted by two halves each comprising one closed turn.

Figure 8 shows a coil constituted by one turn, of which Figure 9 is an exploded view in a plane, Figure 10 being an exploded view of a slightly modified form of the coil shown in Figure 8.

The construction of the coil system of Figure 12, constituted by two coils, will be explained with reference to Figure 11, and Figures 13 and 14 are two different exploded views of the coil system of Figure 12 in a plane.

Fig. 15 is a view showing the coil of Fig. 8 in position on a cathode-ray tube.

Figures 1 and 2 are exploded views of the two turns Since the coil turns are 2,722,5Zi Patented Nov. 1, 1955 constituting a coil comprising two halves according to one embodiment of the invention.

The turns are constituted by ribbon-like pieces of U-shaped form, the two limbs 1, 2 and also the limbs 3, 4 being provided at the open ends with ring segmentlike parts 5 and 7.

The ring segment-like parts 5 and 7 terminate in straight parts 6 and 3, respectively, which serve as current supply conductors for the coil. The extremities of the ribbonlike piece of Figure 1 are designated a and b and those of the piece of Figure 2 are designated c and d.

The ribbon-like pieces may be produced by a stamping operation on a sheet of suitable conductive material, such as copper, brass or aluminium. The thickness of such a sheet and hence of the turns may be, for example, 1.5 mm.

With a thickness of such order of magnitude, each piece is easily deformable so that the stamping can be bent into the desired shape and yet the turns thus produced have sufficient rigidity to ensure a self-supporting coil construction.

The flat pieces shown in Figures 1 and 2 are subsequently bent into the shape shown in Figures 3 and 4-, respectively.

The shape shown in Figure 3 is obtained by bending the parts to the right of the dotted line 9-5 in Figure 1 forward and at right angles to the plane of the drawing. Subsequently, the short limb 11 of the U-shaped piece is bent substantially in the shape of a circle until the shape corresponds to the periphery of the cathode-ray tube.

The illustrated construction shows a coil which cooperates with a cylindrical portion of the cathode-ray tube. However, as a rule, a portion of the coil surrounds a cylindrical portion of the tube and another portion surrounds a conical portion of the tube. in this case the parts 1 and 2 which are shown as straight, are gradually bent conically towards the part 11, the part 11 being shaped to conform with the larger diameter, resulting in bent part 11 embracing the tube over a smaller number of degrees.

The shape of the turn shown in Figure 4 is obtained by bending the ribbon-like piece of Figure 2. For this purpose the parts to the right of the dotted line 1010 are likewise bent until they are at right angles to the plane of the drawing and directed forward.

Subsequently, the short limb 12 is bent into the correct shape.

The halves of the coil are then assembled by connecting the ends b and d by welding or soldering.

Figure 5 shows the assembled coil surrounding a templet 13, the latter being shown only diagrammatically. The cylindrical templet, which has the same diameter as the cathode-ray tube for which the coil is intended, serves, as will appear hereinafter, for correcting the adjustment of the halves of the coil and of two coils, for example, the line coil and the image coil in a television apparatus.

The other end of the coil has the shape shown in Figure 6.

The coil is connecetd during operation through the ends a and c to the secondary terminals of a matching transformer, a sawtooth current flowing through the primary winding of the transformer.

If the sense of the current in the coil at a in Figure 5 corresponds at a certain moment to the sense of arrow 14, the current flows at 1 at right angles to the direction of the plane of the drawing and backwards through the limb 1 extending in the longitudinal direction of the templet (or tube) 13 and subsequently, as shown in Figure 6, through the bent part 11 towards the limb 2, whereafter this current in this limb is directed forward in Figure 5.

Subsequently, the current follows the direction indicated by arrow 15 and flows through the limb 4 backwards towards the bent part 12 in Figure 6 and thence towards the limb 3 which is traversed in forward direction in Figure 5, whereafter the current leaves the coil at c.

The pair of limbs 1 and 4, which belong to different pieces, as shown in Figures 1 to 4, inclusive, is thus traversed by the current in backward direction and the pair of limbs 2, 3 is traversed in forward direction.

The two parts of limbs are positioned diametrically opposite one another.

Figure 6, furthermore, shows that the bent parts 11 and 12 overlap in part. This fact may be utilized to interconnect these parts with electrical insulation at one or more points in order to obtain a sufliciently rigid construction.

This construction becomes even more rigid in the case of, for example, a television apparatus comprising a line coil and an image coil, both of which are formed in the whereas the terminal surfaces of the shape shown in Figure 5 may be shifted slightly relative to one another. The latter surfaces may be interconnected with electrical insulation at one or more points.

If the short parts 11 and 12 are also chosen to have different lengths, these parts will group themselves about the bent parts 11 and 12 of the other coil, which affords further possibilities of securing.

For the calte of simplicity, Figure 5 only shows the parallel limbs 16, 17, 18, 19 of the second coil, in this case, the image deflection coil.

As shown in the figure, the dimension of these limbs, measured along the circumference of the tube or templet 13, is smaller than that of the limbs 1, 2, 3, 4.

In fact, it has been found that eddy currents are produced due to the magnetic field generated in the limbs It should be noted, however, that the image coil does not produce any troublesome eddy currents in the line deflection coil due to the low frequencies of the image sawtooth current.

For adjusting the coil or the coil system, templet 13 is employed, since it is provided with a plurality of elevated ribs in the longitudinal direction. For the sake of clarity in the drawing, only two such ribs are indicated by 28 and 21 in Figure 5, but their number is equal to the number of limbs of the coil or the coil systern, their position and width along the circumference of the templet being chosen such that the limbs of the coil or the coil system just fit between the ribs. The position and the spacing between the limbs are thus completely fixed so that the coil need not be deformed when being mounted about the cathode-ray tube. It should be, furthermore, noted that the shape of the surface scanned by the cathode-ray may be influenced by the choice of the spacing between the limbs of one pair, for example, between the limbs 2, 3 or 1, 4 in Figure 5, so that cushionor barrel-like distortion is avoided.

The coil according to the embodiment shown in Figure 7 comprises two closed filiform halves 22 and 23, which are arranged about the cathode-ray tube in a manner which is clear from the figure without any further explanation.

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Each winding comprises a loop-like part 24, 25 respectively, a core 26 of a transformer being passed through-the loops formed. The secondary windings of the transformer are constituted by the turns 22 and 23, the core being surrounded by the primary winding 27.

In the embodiments of the invention hitherto shown, the coil comprises two halves and each half of the coil comprises one turn.

According to further embodiments of the invention, the coil or the coil system comprises only one turn.

The coil shown in Figure 8 comprises two closed conductors 28 and 29 surrounding the cathode-ray tube, which conductors are at right angles to the longitudinal axis of the tube as shown in Fig. 15 and are spaced a small distance apart.

The said conductors are connected by means of two conductors 30 and 31 extending at least in part along the tube and positioned diametrically with respect to the axis of the tube.

The conductor 31 does not extend entirely along the tube but comprises a loop-shaped part 32, 33, 34 for coupling with a matching transformer.

The sense of current follows from the arrows indi cated in the figure.

A turn of the shape shown in Figure 8 may be manufactured from sheet metal by punching it therefrom in a shape as shown in Figure 9. Identical parts are indicated by corresponding reference numerals.

The coil is formed in the required shape by bending, which, as before, may be effected with the use of a templet, whereafter the extremities 35 and 36 are welded together.

Thus, only one welding spot is required in contradistinction to, for example, the coil shown in Figure 5, which has a welding spot b, c and welds for the supply wires at a and c.

If a predetermined distribution of current along the circumference of the tube is desired, this may be ensured by constituting the limbs 30 and 31 by parallel conductors as shown in Figure 10 for two parallel ribs 30, 30" and 31', 31".

For obtaining two relatively perpendicular deflection fields such as the lineand image-deflection fields in television apparatus, two coils each of the shape shown in Figure 8 may be arranged about the tube but displaced by 90.

However, in one embodiment of the invention, said two coils may be combined while nevertheless retaining the advantage that the coil system may be stamped from sheet metal in one piece.

For the sake of clearness, such a combined coil system is shown diagrammatically in Figure 11.

One current circuit comprises a coupling turn 38, a closed conductor 39, a limb 40, a closed conductor 41, a limb 42, and supply and discharge conductors 43 and 44.

If the closed conductor 41 exhibits, for example, rotational symmetry, the potential difference between the points 45 and 46, which are shifted by with respect to the points 47 and 48, will be nil.

In this case a second current circuit shown in dotted lines and comprising a coupling turn 49, a supply condue tor 50, a closed conductor 51, a limb 52, a limb 53 and a discharge conductor 54 may be connected to the said points 45 and 46 without this circuit being traversed by currents originating from the circuit shown in full line and, conversely, since the points 47 and 48, which are regarded as belonging to the last-mentioned circuit, do not exhibit a potential difference.

Figure 12 shows a construction of such a combined coil system, in which the reference numerals correspond to those of Figure 11. It affords electrical and mechanical advantages to arrange the closed conductors 39 and 51 in one plane, one conductor having an inner diameter such that it is capable of embracing the other conductor without making electric contact therewith.

Figure 13 shows the manner in which the coil system of Figure 12 may be stamped from sheet metal in one piece; the system shown in Figure 12 can be imagined to be interrupted at the coupling turns 38 and 49. In this case only one welding spot is required for each circuit.

However, stamping from a sheet of metal as shown in Figure 13, involves a considerable loss of material.

Consequently, it is preferable that the welding spots should be chosen at the points 46 and 47 of Figure 12, requiring a stamping as shown in Figure 14. This figure also shows the manner in which the current supply conductors 40, 42, 52, 53 may be realized in the form of a plurality of parallel conductors as indicated by accents in the figure.

The figure clearly shows that this stamping may be obtained from a plate 55 with small loss of material. The die is moved in such manner that the shape shown is first stamped completely and susbequently the shapes A, B, C etc., as shown diagrammatically, are stamped. It should be noted that subdivision of the supply conductors into parallel conductors such, for example, as at 53' and 53" in Figure 14, can serve not only to ensure a predetermined distribution of current along the periphery of the tube but also contributes to a decrease in the eddy-current losses brought about in one coil by the other coil.

While the invention has thus been described with specific examples and in specific embodiments, other modifications will be readily apparent to those skilled in the art without departing from the spirit and scope of the invention as defined in the appended claims.

What I claim is:

1. A deflecting coil for a cathode ray tube having a given longitudinal axis comprising a first pair of axiallyspaced flat annular conductors each encircling said tube and arranged at right angles to the longitudinal axis thereof, a second pair of elongated flat conductors mounted diametrically opposite one another on opposite sides of the tube with their flat sides substantially parallel to thelongitudinal axis of the tube, the ends of one of said second pair of conductors being connected to portions of the first pair of conductors lying on the same side of the tube, the ends of the other of said second pair of conductors being connected to portions of the first pair of conductors 1ying on the opposite side of the tube, and means for coupling electrical energy to said conductors.

2. A deflecting coil as claimed in claim 1 in which each of the second pair of conductors comprises a parallel combination of conductors spaced apart a relatively small distance.

3. A deflecting coil as claimed in claim 1 in which the coil is constituted by a ribbon-like unitary rigid conductor.

4. A deflecting coil system for a cathode-ray tube comprising two coils as claimed in claim 1 in which the two coils have a common annular conductor at one end, and the second pairs of conductors are displaced about along the periphery of the tube.

5. A deflecting coil as claimed in claim 1 in which the coil has a filliform shape.

6. A deflecting coil for a cathode ray tube having a given longitudinal axis comprising a first pair of axiallyspaced flat annular conductors each encircling said tube and arranged at right angles to the longitudinal axis thereof and a second pair of elongated flat conductors mounted diametrically opposite one another on opposite sides of the tube with their flat sides substantially parallel to the longitudinal axis of the tube, the ends of one of said second pair of conductors being connected to portions of the first pair of conductors lying on the same side of the tube, the ends of the other of said second pair of conductors being connected to portions of the first pair of conductors lying on the opposite side of the tube, one of said second pair of conductors including means for coupling electrical energy into said coil.

7. A deflecting coil as claimed in claim 6 in which the coupling means comprises a coupling loop formed by a portion of said one conductor.

References Cited in the file of this patent UNITED STATES PATENTS 1,789,129 Apple Jan. 13, 1931 1,834,925 Apple Dec. 8, 1931 2,100,618 Urtel Nov. 30, 1937 2,186,595 Ruska Ian. 9, 1940 2,208,939 Ruska July 23, 1940 2,324,089 Johnson July 13, 1943 2,490,181 Weathers Dec. 6, 1949 2,505,011 Smyth Apr. 25, 1950 2,550,592 Pearce Apr. 24, 1951 2,578,343 Ekvall Dec. 11, 1951 

